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What is the smallest positive integer n such that, out of the n unit fractions 1/k where 1≤k≤n, exactly half of the fractions give a terminating decimal?

 Aug 8, 2019
 #1
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Isn't it 6 integers as follows:

 

2, 3, 4, 5, 6, 7.

 

1/2, 1/3, 1/4, 1/5, 1/6 and 1/7 - which gives 3 terminating and 3 non-terminating

So, the smallest positive integer n = 7

 Aug 8, 2019
 #2
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you have to start with k=1.

 

The answer is 12

Rom  Aug 9, 2019

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